Apparatus for performing an electrosurgical procedure

ABSTRACT

A surgical instrument is provided and includes a housing having a shaft. An end effector assembly operatively connects to the shaft and has a pair of first and second jaw members. A jaw insert is operably associated with the first and second jaw members. The jaw insert includes one or more cam slots defined therein configured to receive a cam pin that upon movement thereof rotates the first and second jaw members from an open position to a clamping position and an opening defined therein configured to securely house a pivot pin that provides a point of pivot for the first and second jaw members. The jaw insert is manufactured from an insulative medium to dielectrically isolate the first and second jaw members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/924,795, filed Oct. 28, 2015, which is a continuation of U.S. patentapplication Ser. No. 13/947,991, filed Jul. 22, 2013, now U.S. Pat. No.9,192,433, which is a continuation of U.S. patent application Ser. No.12/792,001, filed Jun. 2, 2010, now U.S. Pat. No. 8,491,624, the entirecontents of each of these applications is hereby incorporated byreference.

BACKGROUND 1. Technical Field

The present disclosure relates to an apparatus for performing anelectrosurgical procedure. More particularly, the present disclosurerelates to an electrosurgical apparatus including an end effectorassembly having a pair of jaw members with a jaw insert providing amechanical advantage at the end effector while maintaining an electricalinsulative barrier between seal plates associated with the jaw membersand one or more of operative components associated with the endeffector.

2. Description of Related Art

Electrosurgical instruments, e.g., electrosurgical forceps (open orclosed type), are well known in the medical arts and typically include ahousing, a handle assembly, a shaft and an end effector assemblyattached to a distal end of the shaft. The end effector includes jawmembers configured to manipulate tissue (e.g., grasp and seal tissue).Typically, the electrosurgical instrument is operatively and selectivelycoupled to an RF power source (e.g., RF generator) that is in operativecommunication with a control system for performing an electrosurgicalprocedure. Electrosurgical forceps utilize both mechanical clampingaction and electrical energy to effect hemostasis by heating the tissueand blood vessels to coagulate, cauterize, seal, cut, desiccate, and/orfulgurate tissue.

Typically, the jaw members include a respective highly conductive sealplate and are pivotably coupled to one another via one or moremechanical interfaces that provide a point of pivot for one or both ofthe jaw members. For example, in certain instances, a cam slot includinga cam pin operably disposed therein and a pivot pin may be operablycoupled to the end effector and/or one or both of the jaw members. Inthis instance, the cam slot, cam pin and pivot pin collectively pivotand close one or both of the jaw members. For added structuralintegrity, the cam slot, cam pin and pivot pin may be fabricated frommetal. However, because the metal typically utilized in fabricating thecam slot, cam pin and pivot pin is highly conductive, the cam slot, campin and pivot pin need to be electrically insulated from the seal platesassociated with the respective jaw members.

In certain instances, to facilitate moving the jaw members from an openposition for grasping tissue to a closed position for clamping tissue(or vice versa) such that a consistent, uniform tissue effect (e.g.,tissue seal) is achieved, one or more types of suitable devices may beoperably associated with the electrosurgical forceps. For example, insome instances, one or more types of springs, e.g., a compressionspring, may operably couple to the handle assembly associated with theelectrosurgical forceps. In this instance, a spring is typicallyoperatively associated with a drive assembly to facilitate actuation ofa movable handle associated with the handle assembly to ensure that aspecific closure force between the jaw members is maintained within oneor more suitable working ranges.

An increased mechanical advantage and/or mechanical efficiency withrespect to transferring the closure force(s) from the handle assembly tothe jaw members while maintaining an electrical insulative barrierbetween the seal plates associated with the jaw members may proveadvantageous in the relevant art.

SUMMARY

The present disclosure provides a forceps. The forceps includes ahousing having one or more shafts that extend therefrom that define alongitudinal axis therethrough. An end effector assembly operativelyconnects to a distal end of the shaft(s) and has a pair of first andsecond jaw members. The first and second jaw members movable relative toone another from an open position wherein the first and second jawmembers are disposed in spaced relation relative to one another, to aclamping position wherein the first and second jaw members cooperate tograsp tissue therebetween. A jaw insert is operably disposed within oneor both of the first and second jaw members. The jaw insert includes oneor more cam slots defined therein configured to receive a cam pin thatupon movement thereof rotates the first and second jaw members from theopen position to the clamping position and an opening defined thereinconfigured to securely house a pivot pin that provides a point of pivotfor the first and second jaw members. The jaw insert may be manufacturedfrom an insulative medium to dielectrically isolate the first and secondjaw members.

In an embodiment, the forceps includes a housing having one or moreshafts that extend therefrom that define a longitudinal axistherethrough. An end effector assembly operatively connects to a distalend of the shaft(s) and has a pair of first and second jaw members. Thefirst and second jaw members movable relative to one another from anopen position wherein the first and second jaw members are disposed inspaced relation relative to one another, to a clamping position whereinthe first and second jaw members cooperate to grasp tissue therebetween.A jaw insert is operably disposed within one or both of the first andsecond jaw members. The jaw insert includes one or more cam slotsdefined therein configured to receive a cam pin that upon movementthereof rotates the first and second jaw members from the open positionto the clamping position and an opening defined therein configured tosecurely house a pivot pin that provides a point of pivot for the firstand second jaw members. A spring operably couples to the jaw insert andis configured to provide a camming force to the cam slot and a portionof a sealing force to the jaw members when the first and second jawmembers are in a clamping position.

In one particular embodiment, a spring operably couples to the jawinsert, and provides a camming force to the cam slot and a sealing forceto the jaw members when the first and second jaw members are in aclamping position.

In one particular embodiment, the jaw insert is manufactured from aninsulative medium to dielectrically isolate the first and second jawmembers and a spring operably couples to the jaw insert. The spring isconfigured to provide a camming force to the cam slot and a portion of asealing force to the first and second jaw members when the first andsecond jaw members are in a clamping position.

The present disclosure also provides a method of manufacture for anelectrosurgical instrument. The method includes an initial step offabricating a housing including a handle assembly and one or more shaftswherein the shaft(s) defines a longitudinal axis. A step of the methodincludes fabricating an end effector, wherein the end effector isoperably positionable at a distal end of the shaft(s). The end effectorincludes a pair of first and second jaw members. One or both of thefirst and second jaw members includes an opening. Fabricating a jawinsert including one or more cam slots defined therein configured toreceive a cam pin that upon movement thereof rotates the first andsecond jaw members from an open position to the clamping position and anopening defined therein configured to securely house a pivot pin thatprovides a point of pivot for the first and second jaw members is a stepof the method. Positioning the insulative jaw insert within the openingof one of the first and second jaw members is another step of themethod.

BRIEF DESCRIPTION OF THE DRAWING

Various embodiments of the present disclosure are described hereinbelowwith references to the drawings, wherein:

FIG. 1A is a side, perspective view of an endoscopic bipolar forcepsshowing an end effector assembly including jaw members according to anembodiment of the present disclosure;

FIG. 1B is a side, perspective view of the endoscopic bipolar forcepsdepicted in FIG. 1A illustrating internal components associated with ahandle assembly associated with the endoscopic bipolar forceps;

FIG. 2A is a perspective view of a jaw member illustrated in FIGS. 1Aand 1B including a jaw insert according to an embodiment of the presentdisclosure;

FIG. 2B is an exploded view of the jaw member and jaw insert illustratedin FIG. 2A;

FIG. 3A is a schematic view of a jaw member including a jaw insertaccording to another embodiment of the present disclosure;

FIG. 3A-1 is a cross-section view taken along line segment 3A-1 of FIG.3A;

FIG. 3B is a schematic view of a jaw member including a jaw insertaccording to an alternate embodiment of the jaw insert illustrated inFIG. 3A;

FIG. 3C is a schematic view of a jaw member including a jaw insertaccording to an alternate embodiment of the jaw insert illustrated inFIG. 3A;

FIG. 3D is a schematic view of a jaw member including a jaw insertaccording to an alternate embodiment of the jaw insert illustrated inFIG. 3A;

FIG. 4A is a schematic view of a jaw member including a jaw insertaccording to still another embodiment of the present disclosure;

FIG. 4B is a schematic view of a jaw member including a jaw insertaccording to an alternate embodiment of the jaw insert illustrated inFIG. 4A;

FIG. 4C is a schematic view of a jaw member including a jaw insertaccording to an alternate embodiment of the jaw insert illustrated inFIG. 4A;

FIG. 5 is a schematic view of a jaw member including a jaw insertaccording to yet another embodiment of the present disclosure;

FIG. 6 is a schematic view of a jaw member including a jaw insertaccording to still another embodiment of the present disclosure;

FIG. 7A is a perspective view of a spring configuration that may beutilized with the jaw insert depicted in FIGS. 2A-5 or FIG. 6;

FIG. 7B is a perspective view of another type of spring configurationthat may be utilized with the jaw insert depicted in FIGS. 2A-5 or FIG.6;

FIG. 8 is a schematic view of a jaw member including a jaw insertaccording to still another embodiment of the present disclosure; and

FIG. 9 is a schematic view of a jaw member including a jaw insertaccording to yet another embodiment of the present disclosure.

DETAILED DESCRIPTION

Detailed embodiments of the present disclosure are disclosed herein;however, the disclosed embodiments are merely exemplary of thedisclosure, which may be embodied in various forms. Therefore, specificstructural and functional details disclosed herein are not to beinterpreted as limiting, but merely as a basis for the claims and as arepresentative basis for teaching one skilled in the art to variouslyemploy the present disclosure in virtually any appropriately detailedstructure.

With reference to FIGS. 1A and 1B, an illustrative embodiment of anelectrosurgical apparatus (e.g., bipolar forceps 10) for performing anelectrosurgical procedure is shown. Bipolar forceps 10 is operativelyand selectively coupled to an electrosurgical generator (not shown) forperforming an electrosurgical procedure. As noted above, anelectrosurgical procedure may include sealing, cutting, cauterizingcoagulating, desiccating, and fulgurating tissue all of which may employRF energy. The generator may be configured for monopolar and/or bipolarmodes of operation. The generator may include or is in operativecommunication with a system (not shown) that may include one or moreprocessors in operative communication with one or more control modulesthat are executable on the processor. The control module (not explicitlyshown) may be configured to instruct one or more modules to transmitelectrosurgical energy, which may be in the form of a wave orsignal/pulse, via one or more cables (e.g., a cable 310) to one or bothseal plates 118, 128.

Bipolar forceps 10 is shown for use with various electrosurgicalprocedures and generally includes a housing 20, an electrosurgical cable310 that connects the forceps 10 to a source of electrosurgical energy(e.g., electrosurgical generator not shown), a handle assembly 30, arotating assembly 80, a trigger assembly 70, a drive assembly 130 (FIG.1B), and an end effector assembly 100 that operatively connects to thedrive assembly 130 that includes a drive rod 150. The drive assembly 130may be in operative communication with handle assembly 30 for impartingmovement of one or both of a pair of jaw members 110, 120 of endeffector assembly 100. End effector assembly 100 includes opposing jawmembers 110 and 120 (FIGS. 1A and 1B) that mutually cooperate to grasp,seal and, in some cases, divide large tubular vessels and large vasculartissues.

With continued reference to FIGS. 1A and 1B, forceps 10 includes a shaft12 that has a distal end 14 configured to mechanically engage the endeffector assembly 100 and a proximal end 16 that mechanically engagesthe housing 20. In the drawings and in the descriptions that follow, theterm “proximal,” as is traditional, will refer to the end of the forceps10 which is closer to the user, while the term “distal” will refer tothe end that is farther from the user.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40.Fixed handle 50 is integrally associated with housing 20 and handle 40is movable relative to fixed handle 50. Movable handle 40 of handleassembly 30 is ultimately connected to the drive assembly 130, whichtogether mechanically cooperate to impart movement of one or both of thejaw members 110 and 120 to move from an open position, wherein the jawmembers 110 and 120 are disposed in spaced relation relative to oneanother, to a clamping or closed position, wherein the jaw members 110and 120 cooperate to grasp tissue therebetween.

Jaw members 110, 120 are operatively and pivotably coupled to each otherand located adjacent the distal end 14 of shaft 12. A respectiveelectrically conductive seal plate 118 and 128 is operably supported onand secured to jaw housings 117 and 127 of respective the jaw members110 and 120, described in greater detail below. For the purposes herein,jaw members 110 and 120 include jaw housings 117 and 127 and sealingplates 118 and 128, respectively. Jaw housings 117 and 128 areconfigured to support the seal plates 118 and 128, respectively.

For a more detailed description of the bipolar forceps 10 includinghandle assembly 30 including movable handle 40, rotating assembly 80,trigger assembly 70, drive assembly 130, jaw members 110 and 120(including coupling methods utilized to pivotably couple the jaw members110 and 120 to each other) and electrosurgical cable 310 (includingline-feed configurations and/or connections), reference is made tocommonly owned U.S. patent application Ser. No. 11/595,194 filed on Nov.9, 2006.

Turning now to FIGS. 2A-2B, and initially with reference to FIG. 2A, jawhousing 117 is shown operably coupled to a jaw insert 200 according toan embodiment of the present disclosure. It should be noted that jawinsert 200 may be operably coupled to either or both of the jaw housings117 and 127. In view thereof, and so as not to obscure the presentdisclosure with redundant information, the operative componentsassociated with the jaw insert 200 are described in further detail withrespect to jaw member 110, and only those features distinct to housing127 will be described hereinafter.

Jaw member 110 and operative components associated therewith may beformed from any suitable material, including but not limited to metal,metal alloys, plastic, plastic composites, and so forth. In theembodiment illustrated in FIGS. 2A and 2B, jaw member 110 is formed frommetal.

A distal end 117 a of the jaw member 110 may be configured to securelyengage the electrically conductive seal plate 118 or, with respect to amonolithic jaw member, form the seal plate 118. As discussed herein, jawmember 110 is monolithic but one such assembled jaw member is disclosedin commonly-owned U.S. patent application Ser. No. 11/827,297.

A proximal end 117 b of the jaw member 110 is configured to securelysupport a portion of the jaw insert 200 in a relatively fixed position.With this purpose in mind, proximal end 117 b has a generallyrectangular configuration including a recess or opening 122 definedtherein that includes geometry of suitable proportion to securely housethe jaw insert 200 (FIG. 2B). In the embodiment illustrated in FIGS.2A-2B, opening 122 of proximal end 117 b includes a generally oval orelliptical configuration defined by a generally oval sidewall 124 havingfour generally arcuate corners (FIG. 2B). More particularly, opening 122and/or sidewall 124 includes a generally oval configuration having aheight, length and width each proportioned to securely house jaw insert200 within the jaw member 110 during the manufacture process of the jawmember 110, end effector 100 and/or forceps 10. A portion of theproximal end 117 b is operably secured to the distal end 14 of the shaft12. More particularly, a portion of proximal end 117 b operably couplesto the distal end 14 and is in operative communication with the driverod 150 of the drive assembly 130 such that movement of the drive rod150 causes one or both of the jaw members 110 and 120 to move from theopened position to the closed or clamping position. For example, in oneparticular embodiment, when the drive rod 150 is “pulled,” i.e., movedor translated proximally, one or both of the jaw members 110 and 120is/are caused to move toward the other. In an alternate embodiment, whenthe drive rod 150 is “pushed,” i.e., moved or translated proximally, oneor both of the jaw members 110 and 120 are caused to move toward eachother. In certain instances, it may prove useful to have a drive rod 150that is flexible. More particularly, in the instance where the drive rod150 is operatively associated with a catheter instrument (e.g., acatheter forceps configured for use in catheter based applications wherethe jaws associated therewith are typically quite small, i.e., 3 mm-5mm), the drive rod 150 may be flexible to accommodate bends typicallyassociated with a shaft of the catheter forceps when the catheterforceps is positioned within a patient and when the jaws are being movedfrom an open configuration for positioning tissue between the jaws, to aclosed configuration for grasping tissue.

Jaw insert 200 defines a cam slot 202 and a pivot pin opening 212 eachconfigured such that one or both of the jaw members, e.g., jaw member110, may pivot with respect to the other jaw member, e.g., jaw member120, while providing electrical insulation for the cam slot 202 and apivot pin 211 (see FIG. 1A, for example) from one or more electricalcomponents associate with one or both of the jaw members 110 and 120. Tothis end, jaw insert 200 may be made from a non-conductive (or partiallyconductive) material. Suitable materials that jaw insert 200 may beformed from include but are not limited to plastic, ceramic, and soforth. For example, jaw insert 200 may be made from injected moldedplastic, such as, for example, a plastic of the type selected from thegroup consisting of thermoplastics and thermoset plastics. In theembodiment illustrated in FIGS. 2A and 2B, jaw insert 200 is made athermoset type plastic. In one particular embodiment, jaw insert 200 ismade from a thermosetting plastic, such as, for example, Duroplast.

Jaw insert 200 includes a generally rectangular base 206 including agenerally oval or elliptical raised portion 208 of suitable proportionand configured to securely engage sidewall 124 of the opening 122 (seeFIG. 2A in combination with FIG. 2B). A generally circular cut-out 210 ais positioned at a distal end of the jaw insert 200 and is configured tosecurely engage a corresponding detent or protrusion 210 b (shown inphantom, see FIGS. 2A and 2B) operably disposed on the jaw member 110.This cut-out 210 a and detent 210 b configuration facilitatesmaintaining the jaw insert 200 and jaw member 110 in alignment andsecured engagement with each other.

Jaw insert 200 may be secured to jaw member 110 via any suitablesecurement methods known in the art. For example, securement of jawinsert 200 to jaw member 110 may be accomplished by stamping, byovermolding, by overmolding a stamped non-conductive jaw insert 200and/or by overmolding a plastic injection molded jaw insert 200. All ofthese manufacturing techniques produce a jaw member, e.g., jaw member110, having a jaw insert 200 that is substantially surrounded by the jawhousing 117. Alternatively, jaw insert 200 may be secured to jaw member110 via one or more types of mechanical interfaces. More particularly,jaw insert 200 may be secured to jaw member 110 via a press fit, fictionfit, bayonet fit, etc. In one particular embodiment, jaw insert 200 issecured to jaw member 110 via press fit. In this instance, one or moregrooves or indents (not explicitly shown) may be operably disposed alonggenerally oval sidewall 124. The groove(s) is configured to securely andoperably engage a corresponding detent(s) (not explicitly shown)operably disposed on the jaw insert 200. For example, the correspondingdetent(s) may be operably disposed along an outer periphery of thegenerally oval raised portion 208. The groove(s) and detent(s) maintainthe jaw insert 200 and jaw member 110 in secured engagement when the jawinsert 200 is positioned within the jaw member 110.

Cam slot 202 is of suitable proportion and configured to receive acorresponding camming structure 205, e.g., a cam pin 205, see FIG. 2A,and is operably formed and/or positioned on the jaw insert 200. Moreparticularly, cam slot 200 includes a generally oblique configurationwith respect to a longitudinal axis “B-B” that is parallel tolongitudinal axis “A-A” defined through the shaft 12, see FIG. 2A. Camslot 202 may extend at an angle that ranges from about 5° to about 45°with respect to the longitudinal axis “B-B.” In the embodimentillustrated FIGS. 2A and 2B, cam slot 202 extends at angle that isapproximately equal to 30° with respect to the longitudinal axis “B-B.”Cam slot 202 extends through the jaw insert 200, see FIGS. 2A and 2B.One or more type of lubricious materials 204 (illustrated via hatchingin FIG. 2B), e.g., PTFE, may coat cam slot 202. Coating the cam slot 202with the lubricious material 204 facilitates movement of the cam pin 205within the cam slot 202 when the drive rod is translated distally (orproximally). The angle of the cam slot 202 may be selectively varieddepending upon a particular instrument, use or manufacturing preference.As such, an assembly technician can insert a variety of different jawinserts 200 to accomplish a particular purpose.

An aperture or opening 212 of suitable proportion and configured toreceive a corresponding pivot pin 211 or the like (see FIG. 1A) isoperably formed and/or positioned on the jaw insert 200. Moreparticularly, aperture 212 includes a generally circumferentialconfiguration and is operably disposed at a distal end of the jaw insert200. Aperture 212 extends through the jaw insert 200, see FIGS. 2A and2B. Aperture 212 may be oriented in any other position within the jawinsert 200 depending upon a particular purpose or a particularinstrument.

In an assembled configuration each of the jaw members 110 and 120 arepositioned in side-by-side relation. Cam pin 205 is operably disposedwithin cam slot 202 associated with jaw member 110 and a correspondingcam slot (not explicitly shown) associated with jaw member 120. As notedabove, the cam pin 205 may be operably coupled to the drive rod 150 (orother suitable driving device). A pivot pin 211 is positioned withinopening 212 associated with jaw member 110 and a corresponding opening(not explicitly shown) associated with jaw member 120. The pivot pin 211provides a point of pivot for each of the jaw members 110 and 120. Onceassembled, the jaw members 110 and 120 may be pivotably supported at thedistal end 14 of the shaft 12 by known methods, such as, for example, bythe method described in commonly-owned U.S. patent application Ser. No.11/827,297.

In use, initially jaw members 110 and 120 are in an opened position.Tissue is positioned between the jaw members 110 and 120 and,subsequently, movable handle 40 is moved proximally. Proximal movementof movable handle 40 causes the drive rod 150 to move proximally.Proximal movement of drive rod 150 causes cam pin 205 positioned withinthe cam slot 202 and the cam slot associated with jaw member 120 to moveproximally, which, in turn, causes one or both of the jaw members, e.g.,jaw member 110 to move (e.g., pivot about the pivot pin 211 positionedin opening 212 and the opening associated with jaw member 120) towardthe other jaw member, e.g., jaw member 120, such that tissue is clampedbetween the jaw members 110 and 120. Thereafter, electrosurgical energyis transmitted to the seal plates 118 and 128 of respective jaw members110 and 120 such that a desired tissue effect is caused to the clampedtissue. During transmission of electrosurgical energy to the seal plates118 and 128, jaw insert 200 serves as an electrical insulation medium orbarrier between the seal plates 118, 128 and the cam pin 211 positionedwithin the cam slot 202 (and the cam slot associated with jaw member120), and pivot pin 211 positioned within the opening 212 (and theopening associated with jaw member 120). This configuration alsoprevents and/or impedes electrical shorts from developing between theseal plates 118, 128 and jaw housings 117 and 127, and the cam pin 211positioned within the cam slot 202 (and the cam slot associated with jawmember 120), and pivot pin 211 positioned within the opening 212 (andthe opening associated with jaw member 120). Preventing and/or impedingelectrical shorts from developing between one or more of the operativecomponents associated with the end effector 100 provides improvedtransmission of electrosurgical energy from an electrosurgical powersource to the seal plates 118 and 128.

With reference now to FIGS. 3A-3C an alternate embodiment of a jawinsert 300 is shown. Jaw insert 300 is similar to jaw insert 200 and soas not to obscure the present disclosure with redundant information,only those operative features and components that are unique to jawinsert 300 are described. In the embodiment illustrated in FIG. 3A, jawinsert 300 is described in terms of use with the jaw member 110. In theembodiment illustrated in FIG. 3A, jaw member 110 and operativecomponents associated therewith function in a manner as described abovewith respect to jaw insert 200. Accordingly, only those features andoperative components associated with jaw member 110 that are necessaryto facilitate understanding of the operative components associated withjaw insert 300 is described.

An opening 302 associated with the jaw insert 300 and defined therein isconfigured to house one or more resilient members 350 and a movablemember 304 that includes a cam slot 306 and an opening 305 (similar tothat of opening 212 of jaw insert 200). More particularly, opening 302is dimensioned such the resilient member(s) 350 is capable of flexingand movable member 304 is capable of translating or moving within theopening 302. To this end, opening 302 is defined by four walls of thejaw insert 300 forming a generally square or rectangular configuration.In an embodiment, one or more of the walls, e.g., a bottom wall 301 a,may include a groove or detent that slidable engages a correspondingdetent or groove operably disposed on the movable member 304, e.g., abottom surface 311 of the movable member 304. For example, alongitudinal detent 307 b may extend along a length of the bottom wall301 a of the opening 302 and a corresponding longitudinal groove 307 aof suitable proportion may extend along a length of the bottom surface311 of the movable member 304, see FIG. 3A-1. In this instance, thegroove 307 a and detent 307 b configuration facilitates movement of themovable member 304 with respect to the jaw insert 300 and maintains themovable member 304 in substantial alignment with the longitudinal axis“A-A,” see FIG. 3A in combination with 3A-1. A proximal wall 301 b ofthe opening 302 is operably coupled to the resilient member 350 via oneor more suitable coupling methods, e.g., adhesive, solder, etc. Aportion of the movable member 304 operably couples to the resilientmember 350.

Movable member 304 is suitably proportioned to movably reside within theopening 302. Cam slot 306 is operably disposed within the movableportion 304 and is similar to cam slot 204. One distinguishing featureof cam slot 306 when compared to cam slot 202 is the position of camslot 306 with respect to jaw insert 300. That is, cam slot 304 ispositioned closer to a distal end of the jaw insert 300 than cam slot202 is positioned with respect to a distal end of the jaw insert 200.Positioning the cam slot 304 closer to the distal end of the jaw insert300 provides more area for the resilient member 350 to expand andcontract when the jaw members 110 and 120 are moved from an opened toclosed or clamping position or vice versa. In one particular embodiment,a notched area 308 disposed adjacent a proximal end of the movablemember 304 is dimensioned to securely house a portion of resilientmember 350. In an alternate embodiment, a proximal end of the movablemember 304 is configured to securely house a portion of resilient member350.

One or more types of resilient member(s) 350 are operably associatedwith the jaw insert 300. More particularly, one or more types of springsare utilized to generate a closure force at the jaw members 110 and 120of the end effector 100 when the jaw members 110 and 120 are in a closedor clamped position. The resilient member 350 cooperates with the driveassembly 130 to provide the necessary closure force for sealing tissue.More particularly, the resilient member 350 offloads some of the forcesnecessary to generate the appropriate closure force which is typicallyincurred in the housing 20. A compression spring 131 (see FIG. 1B) inhousing 20 and the resilient member 350 are configured to mechanicallyassist a user when moving the handle 40 to generate the necessary driveforces.

One or more suitable types of springs may be utilized to generate asealing force at cam slot 304 of the movable member 304. In theembodiment illustrated in FIG. 3A, a coil spring 350 is operablyassociated with the jaw insert 300. More particularly, a proximal end ofthe coil spring 350 is operably coupled to the proximal wall 301 b ofthe jaw insert 300 and a distal end of the spring 350 is securely housedwithin the notched area 308. The coil spring 350 may have any suitablerating, e.g., in one particular embodiment, spring 350 has a rating ofabout 120 pounds per square inch to offset all of the closure forcesfrom the handle assembly 30 and the drive assembly 130. Lesser springratings are envisioned when the coil spring 350 or other type of springis manufactured to assist with sealing pressures.

In an alternate embodiment, spring 350 may be a leaf spring 360, seeFIG. 3B, for example. In the embodiment illustrated in FIG. 3B, proximalend of the leaf spring 360 couples to the proximal wall 301 b of the jawinsert 300 and a pair of distal ends of the leaf spring 360 couples to aproximal end of the movable member 304. Each of the proximal and distalends of the leaf spring 360 couples to a respective proximal wall 301 bof the jaw insert and proximal end of the movable member 304 by methodspreviously described above.

In an alternate embodiment, spring 350 may be a torsion spring 370, seeFIG. 3C, for example. In the embodiment illustrated in FIG. 3C, proximalend of the torsion spring 306 couples to the proximal wall 301 b of thejaw insert 300 and a distal end of the torsion spring 370 couples to aproximal end of the movable member 304. The proximal end of the torsionspring 370 couples to the proximal wall 301 b of the jaw insert 300 viaa pin 303 (or other suitable structure or other suitable methods, e.g.,such as the methods previously described above with respect to spring350). The distal end of the spring 370 couples to the proximal end ofthe movable member 304 by methods previously described above withrespect to spring 350.

Operation of the forceps 10 with an jaw insert 300 that includes aresilient member 350 is described below in terms of use with a coilspring 350 illustrated in FIG. 3A.

In use, initially jaw members 110 and 120 are in an opened position.Tissue is positioned between the jaw members 110 and 120 and,subsequently, movable handle 40 is moved proximally. Proximal movementof movable handle 40 causes the drive rod 150 to move proximally.Proximal movement of the drive rod 150 causes a cam pin, e.g., cam pin205, positioned within the cam slot 306 on movable member 304 to moveproximally against the bias of the coil spring 350, which, in turn,causes one or both of the jaw members, e.g., jaw member 110 to movetoward the other jaw member, e.g., jaw member 120, such that tissue isclamped between the jaw members 110 and 120. When the cam pin 205 ismoved, i.e., “pulled,” to a set position, e.g., a position when the jawmembers 110 and 120 are in the closed or clamped position, the biasedcam pin 205 generates a sealing or closure force at the jaw members 110and 120. Thereafter, the previously described steps with respect to jawinsert 200 may be carried out. The combination of jaw insert 300 with acoil spring 350 assists in providing a consistent, uniform tissueeffect, e.g., tissue seal, and an electrical insulation barrier betweenthe seal plates 118, 128 and one or more of the operative componentsdescribed above with respect to jaw insert 200. The combination of jawinsert 300 and coil spring 350 (or other described springs, e.g., leafspring 360) may provide an additional mechanical advantage when employedwith surgical devices with small jaws, such as, for example, flexiblecatheters that employ small jaws configured for jaw insertion intosurgical ports of relatively small dimension. Additionally, the coilspring 350 (or other biasing member) may be configured to generate allof the closure force necessary to seal tissue.

With reference now to FIG. 3D an alternate embodiment of a jaw insert400 is shown. Jaw insert 400 is similar to jaw inserts 200 and 300. Soas not to obscure the present disclosure with redundant information,only those operative features and components that are unique to jawinsert 400 are described. For illustrative purposes, jaw insert 400 andoperative components associated therewith are described in terms of usewith jaw member 120.

A proximal portion of the jaw insert 400 includes a notched area orchannel 402 defined by two raised portions 404 and 406. The notched area402 is proportioned and configured to securely house a portion of aproximal end of a torsion spring 470, described in greater detail below.A raised protrusion or pin 408 of suitable proportion is configured tosecurely engage an opening at the proximal end of the torsion spring470. A cam slot 410 similar to previously described cam slots, e.g., camslot 306, is operably disposed on the jaw insert 400. Cam slot 410houses a cam pin 414 that is movable within cam slot 410 from a proximalposition to a distal position or vice versa. A distinguishing feature ofthe cam slot 410 when compared to previously described cam slots, e.g.,cam slot 306, is that cam slot 410 is orientated in a direction that issubstantially parallel, i.e., horizontal, to the longitudinal axis“A-A.” Cam slot 410 is in substantial alignment with an opening 412 thathouses a pivot pin, e.g., pivot pin 211. Opening 412 is configured in amanner similar to previously described openings, e.g., 212.

In the embodiment illustrated in FIG. 3D, torsion spring 470 is operablyassociated with the jaw insert 400. More particularly, an opening 472(shown engaged with protrusion 408 and as such not explicitly visible)is defined at the proximal end of the torsion spring 470 and is securelyengaged to protrusion 408. An elongated portion 416 defining a slot 418extends from opening 472 of the torsion spring 470 and engages cam pin414 of cam slot 410. A proximal end of the torsion spring 470 issecurely housed within the notched area 402 of the jaw insert 400. Moreparticularly, a finger 474 of suitable proportion extends from theproximal end of the torsion spring 470 and is securely housed within thenotched area 402.

Operation of the forceps 10 with jaw insert 400 that includes a torsionspring 470 is substantially similar to the operation of a forceps 10that includes a spring depicted in FIGS. 3A-3C. One distinguishingfeature of the jaw insert 400 when compared to jaw insert 300 utilizedis that jaw member 120 pivots with respect to the jaw member 110.

With reference now to FIGS. 4A-4C, and initially with reference to FIG.4A, an alternate embodiment of jaw inserts 200, 300 and 400 is shown anddesignated 500. Jaw insert 500 is similar to jaw inserts 200, 300 and400. So as not to obscure the present disclosure with redundantinformation, only those operative features and components that areunique to jaw insert 500 are described. For illustrative purposes, jawinsert 500 and operative components associated therewith are describedin terms of use with jaw member 110. In the embodiments illustrated inFIG. 4A-4C, jaw member 110 and operative components associated therewithfunction in a manner as described above with respect to the previouslydescribed jaw inserts, e.g., jaw insert 200. Accordingly, only thosefeatures and operative components associated with jaw member 110 thatare necessary to facilitate understanding of the operative componentsassociated with jaw insert 500 are described.

In the embodiments illustrated in FIGS. 4A-4C, one or more types ofresilient or spring-like structures are monolithically formed with thejaw insert 500 during the manufacturing process. Monolithically formingthe jaw insert 500 with a resilient member(s) decreases the amount ofworking components, e.g., coil spring 350, needed to provide the closureor sealing forces at the jaw members 110 and 120, which, in turn,reduces the overall cost in the manufacture of the end effector 100and/or jaw members 110 and 120.

With reference to FIG. 4A, jaw insert 500 includes a monolithicallyformed notched area 502 having suitable dimensions. Notched area 502creates a cantilever spring configuration. More particularly, thecantilever spring configuration is defined by a notched area 502 thatincludes three sidewalls 506 that collectively define a generallytriangular base section 508 of suitable dimensions. A pair of sidewalls510 extends from the base section 508 and defines an upright section 512of suitable dimensions. The upright section 512 is oriented orthogonalwith respect to the longitudinal axis “A-A.” A spring arm section 514 isdefined by three sidewalls 516 extending distally from the uprightsection 512 in a generally oblique manner toward an opening 518 that isconfigured to house a pivot pin, e.g., pivot pin 211 (not shown in thisFIG.). Opening 512 is configured and functions similar to otheropenings, e.g., opening 412, previously described herein. Spring armsection 514 is dimensioned to house a cam pin 504. In the embodimentillustrated in FIG. 4A, spring arm section 514 is proportionally largerthan upright section 512 (see FIG. 4A). More particularly, uprightsection 512 includes a width that is smaller than a width of the springarm section 514. The smaller width of the upright section 512facilitates flexing or pivoting the spring arm section 514 at a distaltip 518 of the upright section 512 when cam pin 504 is moved proximallywithin the spring arm section 514.

In an alternate embodiment jaw insert 500 includes an opening 520 ofsuitable dimensions, see FIG. 4B, for example. Opening 520 is defined byproximal and distal sidewalls 522 and 524, respectively, and upper andlower walls 526 and 528, respectively. A resilient of spring structure530 of suitable proportion is operably associated with the jaw insert500. More particularly, spring structure 530 is monolithically formed,i.e., molded, with the jaw insert 500. Alternatively, spring structure530 may be a separate component, e.g., coil spring 350, leaf spring 360and torsion spring 370, that is operably coupled to the jaw insert 500by methods previously described herein. Spring structure 530 extendsfrom a bottom wall 528 of the jaw insert 500. More particularly, springstructure 530 includes a generally elongated upright portion 532 thatextends in a generally orthogonal orientation from bottom wall 528toward top wall 526. Upright portion 532 includes an arcuate or concavesection 534 that supports an elongated cam slot 536 dimensioned to housea cam pin 538 and configured to move the jaw member 110. Thisconfiguration of an upright portion 532 that includes an arcuate ofconcave section 534 facilitates flexing or pivoting the elongated camslot 536 when cam pin 538 is moved proximally within the elongated camslot 536. Cam pin 538 is configured and operates similar to otherpreviously described cam pins, e.g., cam pin 504.

In an alternate embodiment, jaw insert 500 includes an opening 540configured to house one or more resilient or spring-like structures 542and a movable member 544 that includes a cam slot 546. Movable member544 including cam slot 546 is configured identically to that of thepreviously described movable member 304 including cam slot 306 and, as aresult thereof, will not be described in further detail. In theembodiment illustrated in FIG. 4C, spring-like structures 542 are in theform of two resilient fingers 548 and 550. More particularly, each ofthe fingers 548 and 550 is monolithically formed, i.e., molded, with thejaw insert 500. Finger 548 includes a generally arcuate configurationand extends from a proximal wall 552 of the jaw insert 500 to a proximalend 554 of the movable member 544. Likewise, finger 550 includes agenerally arcuate configuration and extends from proximal sidewall 552of the jaw insert 500 to a proximal end 554 of the movable member 544.

Operation of the forceps 10 with jaw insert 500 that includes amonolithically formed resilient or spring-like structure is identical tothe operation of a forceps 10 that includes a spring depicted in any ofthe FIGS. 3A-3D. As a result thereof, operation of forceps 10 with jawinsert 500 is not described.

With reference now to FIG. 5 an alternate embodiment of the jaw insert200 is shown and designated jaw insert 600. Jaw insert 600 is similar tothe previously described jaw inserts, e.g., jaw insert 200. So as not toobscure the present disclosure with redundant information, only thoseoperative features and components that are unique to jaw insert 600 aredescribed. In the embodiment illustrated in FIG. 5, jaw insert 600 isdescribed in terms of use with each of the jaw members 110 and 120. Inthe embodiment illustrated in FIG. 5, jaw members 110 and 120 functionin a manner as described above with respect to jaw inserts 200 and 400.Accordingly, only those features and operative components associatedwith jaw members 110 and 120 that are necessary to facilitateunderstanding of the operative components associated with jaw insert 600is described.

Jaw insert 600 includes a cam slot 602 configured to house a cam pin 604that is movable within the cam slot 602. Unlike previously described camslots, e.g., cam slot 306, cam slot 602 is positioned adjacent aproximal end 606 of the jaw insert 600. More particularly, cam slot 602is set back closer to the proximal end 606 than a resilient memberoperably associated with the jaw insert 600. An opening 608 extendsthrough the jaw insert 600 and is configured to receive a pivot pin 611(opening 608 is shown engaged with pivot pin 611 and as such notexplicitly visible). In the embodiment, illustrated in FIG. 5, a portionof the pivot pin 611 is dimensioned to securely house a portion of aresilient member 610 that is operably associated with the jaw insert600. In one particular embodiment, opening 608 and/or the pivot pinhoused therein includes a generally circumferential configuration.

A resilient member 610 in the form of a torsion spring 610 is operablyassociated with the jaw insert 600 and operably couples to each of thejaw members 110 and 120. More particularly, a proximal end 612 ofsuitable proportion and having a generally circumferential configurationis dimensioned to securely couple to the pivot pin 611. Two generallyelongated fingers 614 and 616 extend from proximal end 612 adjacent theproximal ends of the jaw members, e.g., proximal end 117 b of jaw member110 and a proximal end 127 b of the jaw member 120 (see FIG. 3D, forexample), and fixedly couple to a respective distal end of the jawmember, e.g., distal end 117 a of jaw member 117 and a distal end 127 aof the jaw member 120. In the embodiment illustrated in FIG. 5, thetorsion spring 610 biases the jaw members 110 and 120 toward each otherto a closed position.

In use, initially jaw members 110 and 120 are biased in a closedposition under the closure and/or sealing force provided by the torsionspring 610. Proximal movement of movable handle 40 causes the drive rod150 to move proximally. Proximal movement of the drive rod 150 causescam pin 604 positioned within the cam slot 602 to move proximallyagainst the bias of the torsion spring 610, which, in turn, causes oneor both of the jaw members, e.g., jaw member 120 to move away from theother jaw member, e.g., jaw member 110, such that tissue is may bepositioned between the jaw members 110 and 120. Once tissue ispositioned between the jaw members 110 and 120 the movable handle 40 isreleased, which, in turn, causes jaw member 120 to move toward jawmember 110 under the biasing force of the torsion spring 610 (e.g., aposition when the jaw members 110 and 120 are in the closed or clampedposition) generate a sealing or closure force at the jaw members 110 and120. Thereafter, the previously described steps with respect to jawinserts previously described, e.g., jaw inserts 200 and 300, may becarried out and the previously described effects to tissue with the samemechanical advantages (e.g., closure and/or sealing force at the jawmembers 110 and 120) is achieved.

With reference now to FIG. 6 an alternate embodiment of a jaw insert 700is shown. Jaw insert 700 is similar to the previously described jawinserts, e.g., jaw insert 400. So as not to obscure the presentdisclosure with redundant information, only those operative features andcomponents that are unique to jaw insert 700 are described. In theembodiment illustrated in FIG. 6, jaw insert 700 is described in termsof use with the jaw member 110. In the embodiment illustrated in FIG. 6,jaw member 110 functions in a manner as described above with respect tojaw inserts 200. Accordingly, only those features and operativecomponents associated with jaw member 110 that are necessary tofacilitate understanding of the operative components associated with jawinsert 700 is described.

Jaw insert 700 includes a cam slot 702 configured to house a cam pin 704that is movable within the cam slot 702. Similar to the cam slot 410 ofjaw insert 400, cam slot 702 is orientated in a direction that issubstantially parallel, i.e., horizontal, to the longitudinal axis“A-A.” Cam slot 702 is in substantial alignment with an opening 706,which is configured in a manner similar to previously describedopenings, e.g., opening 212 that houses a pivot pin 708 (opening 706 isshown engaged with pivot pin 708 and as such not explicitly visible). Inan alternate embodiment cam slot 702 may be angled (e.g., see cam slot306 in FIG. 3A-3C) or curved.

A resilient member 710 in the form of a spring loaded link 710 isoperably associated with the jaw insert 700 and operably couples to thecam pin 704. More particularly, a proximal end 712 of the spring loadedlink 710 operably couples to a proximal end 722 of the jaw insert 700adjacent an upper portion of the jaw insert 700, and a distal end 714 ofthe spring loaded link 710 operably couples to the cam pin 704 forming a“crank-like” mechanical relationship.

One or more types of springs may be utilized to form a spring component713 of the spring loaded link 710. For example, one type of spring thatmay be utilized to form a spring component 713 of the spring loaded link710 may be a stamped spring 716, see FIG. 7A. Alternatively, a torsionspring 718 may be utilized to form a spring component of the springloaded link 710, see FIG. 7B. The springs illustrated in FIGS. 7A and 7Bare two of many springs that me be utilized to form spring component 713of the spring loaded link 710.

In one particular embodiment, a limit band 720 may operably couple tothe spring component 713, e.g., stamped spring 716 (see FIG. 7A, forexample). In this instance, the limit band 720 limits the amount ofdeflection associated with the spring 716. In one particular embodiment,the limiting band 720 functions as a latching device. More particularly,the limit band 720 functions to maintain the jaw members 110 and 120 ina substantially fixed position, e.g., a closed or clamped position. Inone particular embodiment, after tissue has been treated, e.g., sealed,a rigid or strong pushing force unlatches the limit band 720 such thatthe cam pin 704 is allowed to move within the cam slot 702, whereby oneor both of the jaw members 110 and 120 is allowed to move from theclosed to the open position. Moreover, a preload on the limit band 720and/or spring 713 may be configured to help tolerances and deflectionlength.

Operation of a forceps 10 that includes jaw insert 700 with a springloaded link 710 is substantially similar to the operation of a forceps10 that includes jaw insert 300. More particularly, when the cam pin 704is moved. i.e., “pulled,” to a set position, e.g., position when the jawmembers 110 and 120 are in the closed or clamped position, the biasedcam pin 704 generates a sealing or closure force at the jaw members 110and 120. In the instance where a limit band 720 is utilized, the limitband 720 limits the amount of deflection that may be achieved by thespring 716 and/or locks or latches the jaw members 110 and 120 in asubstantially fixed position, e.g., closed or clamped position.Thereafter, the previously described steps with respect to jaw insert300 may be carried out with an additional step of unlatching the limitband 720 such that the jaw members 110 and 120 may return to the initialopen position. The combination of jaw insert 700 including a springloaded link 710 provides a consistent, uniform tissue effect, e.g.,tissue seal, and an electrical insulation barrier between the sealplates 118, 128 and one or more of the operative components describedabove with respect to jaw insert 700. The combination of jaw insert 700including a spring loaded link 710 may provide an additional mechanicaladvantage when employed with surgical devices with small jaws, such as,for example, flexible catheters that employ small jaws configured forjaw insertion into surgical ports of relatively small dimension.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, other spring mechanisms such as, for example,foam, spring washers, bellows and compressed air and so forth, may beoperably associated with any of the aforementioned jaw inserts, e.g.,jaw insert 300, and utilized to generate a closure or sealing force atthe jaw members.

It is contemplated that any of the aforementioned jaw inserts, e.g., jawinsert 300, may be made from a conductive material and utilized toprovide the necessary closure force or a portion thereof to the firstand second jaw members 110 and 120, respectively.

An embodiment of a jaw insert in accordance with the present disclosureis illustrated in FIG. 8 and is designated jaw insert 800. Jaw insert800 may include a cam slot 802 that is angled, arcuate, curved orotherwise shaped to provide a desired range of motion when therespective jaw members 110 and 120 are moving from the open position tothe clamping position and a desired closure and/or sealing force whenthe respective first and second jaw members 110 and 120 are in a closedor clamping position. A cam pin 804 is operably disposed within the camslot 802. An opening 806 is configured to receive a corresponding pivotpin, e.g., pivot pin 211. A distinguishing feature of opening 806 whencompared to previously described openings, e.g., openings 608 and 708,is that opening 806 is positioned adjacent a bottom portion of the jawinsert 800 and distal with respect to the cam slot 802. Positioning theopening adjacent the bottom portion of the insert 800 facilitatesobtaining a desired range of motion of the jaw member 110 and/or the jawmember 120.

An embodiment of a jaw insert in accordance with the present disclosureis illustrated in FIG. 9 and is designated jaw insert 900. Jaw insert900 may include a cam slot 902 that is angled, arcuate, curved orotherwise shaped (e.g., generally “j” shaped) to provide a desired rangeof motion when the respective jaw members 110 and 120 are moving fromthe open position to the clamping position and a desired closure and/orsealing force when the respective first and second jaw members 110 and120 are in a closed or clamping position. In the embodiment illustratedin FIG. 9, a portion 908 of the cam slot 902 may extend back toward aproximal end of the jaw member 110. In this instance, portion 908extends back toward the proximal end of the jaw member 110 and providesadditional closure or sealing force (or range of motion of the first andsecond jaw members) when the respective first and second jaw members 110and 120 are in a closed or clamping position. A cam pin 904 is operablydisposed within the cam slot 902. An opening 906 is configured toreceive a corresponding pivot pin, e.g., pivot pin 211. A distinguishingfeature of opening 906 when compared to previously described openings,e.g., openings 608, 708 and 806, is that opening 906 is positionedadjacent a proximal end of the jaw insert 900 and proximal with respectto the cam slot 902. Positioning the opening adjacent the proximal endof the insert 800 facilitates obtaining a desired range of motion of thefirst jaw member 110 and/or the second jaw member 120.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

1-20. (canceled)
 21. A forceps, comprising: a housing; a shaft extending from the housing and defining a longitudinal axis; an end effector assembly operatively connected to a distal end of the shaft and having first and second jaw members, at least one of the first or second jaw member pivotable relative to the other about a pivot pin between an open position in which the first and second jaw members are disposed in spaced relation relative to one another and a clamping position in which the first and second jaw members cooperate to grasp tissue therebetween under a sealing pressure; a jaw insert operably disposed within at least one of the first or second jaw member, the jaw insert defining an opening configured to securely house the pivot pin and a cam slot configured to receive a cam pin operably disposed within the shaft, the cam slot positioned proximal of the opening; and a biasing member operably engaged with the pivot pin and the at least one of the first or second jaw member, the biasing member configured to provide a portion of the sealing pressure between the jaw members when the first and second jaw members are in the clamping position.
 22. The forceps according to claim 21, wherein the jaw insert is monolithically formed.
 23. The forceps according to claim 21, wherein the biasing member provides the entire sealing pressure between the jaw members when the first and second jaw members are in the clamping position.
 24. The forceps according to claim 21, wherein the biasing member is a torsion spring disposed about the pivot pin.
 25. The forceps according to claim 21, wherein the biasing member includes a first finger engaged with the first jaw member.
 26. The forceps according to claim 25, wherein the biasing member includes a second finger engaged with the second jaw member.
 27. The forceps according to claim 21, wherein the biasing member is configured to provide a constant sealing pressure.
 28. The forceps according to claim 21, wherein the cam pin is configured to engage the cam slot such that proximal movement of the cam pin pivots the jaw members towards the open position.
 29. The forceps according to claim 21, wherein the cam slot is disposed at an angle relative to the longitudinal axis.
 30. The forceps according to claim 21, wherein the jaw insert is manufactured from an insulative medium to dielectrically isolate the first and second jaw members.
 31. The forceps according to claim 21, wherein the jaw insert is overmolded to at least one of the first or second jaw member.
 32. The forceps according to claim 21, further comprising a drive rod extending from the housing, the drive rod engaged with the cam pin to move the cam pin proximally along the longitudinal axis.
 33. The forceps according to claim 32, wherein the drive rod extends through the shaft.
 34. An end effector assembly comprising: first and second jaw members, at least one of the first or second jaw member pivotable relative to the other between an open position in which the first and second jaw members are disposed in spaced relation relative to one another and a clamping position in which the first and second jaw members cooperate to grasp tissue therebetween under a sealing pressure; a jaw insert operably disposed within at least one of the first or second jaw member, the jaw insert defining an opening configured to define a pivot axis of the pivotable jaw member and to define a cam slot configured to receive a cam pin, the cam slot positioned proximal of the opening; and a biasing member engaged with the at least one of the first or second jaw member, the biasing member configured to provide a portion of the sealing pressure of the jaw members when the first and second jaw members are in the clamping position.
 35. The end effector assembly according to claim 34, further comprising a pivot pin defining the pivot axis of the pivotable jaw member.
 36. The end effector assembly according to claim 35, wherein the pivot pin is received within the opening.
 37. The end effector assembly according to claim 36, wherein the biasing member is engaged with the pivot pin. 